.338 Norma Mag.

The .338 Norma Magnum was originally developed as a long-range sport shooting wildcat cartridge by the American sport shooter Jimmie Sloan with the help of Dave Kiff, owner of Pacific Tool and Gauge, who made the reamers and headspace gauges. Barrels were supplied by Rock Creek Barrel Inc. Various twist rates were tried with 5R rifling. It was designed as a way to optimize shooting the 19.44 grams (300.0 grains) 8.59 millimetres (0.338 in) caliber Sierra HPBT MatchKing projectile from actions and magazines that lack the length to handle cartridges exceeding 91.44 mm (3.600 in) in overall length. The 19.44 grams (300.0 gr) 8.59 mm (0.338 in) caliber Sierra HPBT MatchKing projectile was not available when the .338 Lapua Magnum was originally designed (it was optimized for shooting 16.2 g (250 gr) projectiles) and .338 Lapua Magnum cartridges intended for military use are generally loaded with shorter 16.2 g (250 gr) to 18.47 g (285 gr) projectiles. Later the design was purchased by the Swedish ammunition manufacturer Norma. The .338 Norma Magnum cartridge was C.I.P. certified on 26 May 2010 and thus became an officially registered and sanctioned rifle cartridge.